1. Field of the Invention
The present invention relates to a method for measuring the size of a circuit pattern formed on a substrate in an LSI fabrication process, in particular, to a circuit pattern size measuring method for accurately detecting edge positions of a circuit pattern.
2. Description of the Related Art
Conventionally, edge positions of circuit patterns formed on substrates in LSI fabrication process are detected by scanning electron microscopes (SEM). The SEM scans a circuit pattern with an electron beam so as to detect a circuit pattern. Thereafter, the operator manually sets parallel cursors on the circuit pattern obtained as a SEM image. An automatic measuring algorithm is executed for line profile data in the region surrounded by the parallel cursors so as to detect the edge positions of the circuit pattern.
Thus, to designate a measuring region of a circuit pattern for which the automatic measuring algorithm is executed, the operator should manually set the parallel cursors. However, the setting of the parallel cursors deviates depending on each operator. Therefore, the setting accuracy of the circuit pattern required for the automatic measuring algorithm cannot be always satisfied. In addition, available automatic measuring algorithms (such as threshold method, linear regression method, and maximum differential method) sometimes result in deviation of measured values or measurement error depending on parallel cursors being set. Moreover, the manual setting of parallel cursors lowers the operability and requires longer measurement time. The present invention is made to solve such problems.